Static electricity has been characterized in several ways: as positive or negative charged particles, as an excess of electrical charges; as charge imbalances in different regions on or in a substance; as a separation of charges. Such charges build up in a variety of circumstances, and in the normal course of things, the excess charge is dispersed or neutralized in materials, or by atmospheric conditions, or they can be discharged by bonding to earth ground or another sink that can absorb them. This transfer of charge is commonly called ESD (for ElectroStatic Discharge), and takes place under many conditions and with a wide range of charge accumulation and resultant voltages and currents. When excess charge can be dissipated or drained to earth ground as it builds up, the danger to people and equipment from ESD can be minimized. However, when the charge cannot be drained or dissipated it can accumulate to such a degree that an electrostatic discharge is damaging.
There are many places in which static electricity builds up with no way to drain it via electrical bonding to an earth ground. Many devices and methods have been developed that attempt to deal with this problem. Static electricity is a tremendous problem in the manufacture of electronic components. In 2003, it was estimated that despite active programs to deal with ESD, the global electronic industry lost approximately $84 billion USD due to damage from ESD. The industry worldwide has worked for years to limit the pulse damage caused by ESD—whether from humans or charged devices. Some products for use in these areas utilize an excessive number of charged ions to help neutralize the static charge build-up in nearby air. The use of coatings, sprays, and embedded conductive particulates (e.g., carbon black) are used to dissipate excess charge and carry it to ground. Corona-discharge devices are also used, and allow ESD to ionize atoms and molecules in the air as the charge streams off the tip.
Aerospace provides other examples of the hazards of the buildup of excess charge. Spacecraft have no robust way of disposing of static electricity as it accumulates. Spacecraft vessel components (frame, trusses, hull) act as a massive sink or ground reference plane, and excess charge is theoretically drained or neutralized there (e.g., ISS SSP 30240 in re: conductive structures providing a stable sink). The problem is exacerbated as the vessel moves through the plasma of space, and even more charge accumulates over time. Astronauts must deal with static shocks between themselves and their equipment caused by the build-up of charge. Aircraft accumulate excess charge as they move through the air or even in rain (“precipitation static”), and this must be dissipated to avoid damage to equipment and cause radio interference.
Still another example of the dangers of charge accumulation is the hazard of premature detonation of solid propellants, pyrotechnics and explosive charges due to ESD. Procedures have been developed over time to keep ordnance safe as it is mounted onto and de-mounted off military aircraft, and in each of these care is taken to bond the ordnance to a ground plane. Field radios are susceptible to damage from ESD. Helicopters rotors generate visible sparks as they land in dusty environments due to charged particle accumulation. Rescue crews have to deal with high voltage ESD in cables lowered to the ground from helicopters. Aerospace avionics have to be shielded especially to protect them from charge buildup and ESD.
This invention describes an apparatus by which static electricity, or charged particles, can be neutralized or dissipated without the need for an earth ground or atmosphere.
Much background art exists with regard to static electricity: its generation, accumulation, methods of dissipation, and controlling its discharge. There are many methods for dispersing or neutralizing excess charge, such as sprays, polar molecules and carbon black embedded in work surfaces and floors to make them conductive. Air ionization is a popular method of neutralizing a static charge in the air, by emitting charges opposite to those in the air. Corona discharge from fine-pointed needles or wicks is also used to control ESD, the excess charge being emitted to the atmosphere via the needle. Even small amounts of excess charge can damage semiconductor devices, and one method for dealing with this is to create dissipative structures within the chip design. Devices and methods that can actually drain the static charges (e.g., the use of a ground strap on the wrist of an electronics worker) require bonding to an earth ground.
Some extant devices and methods for controlling ESD simply disperse or dissipate charge, but do not get rid of it. Other methods such as air ionization, or corona discharge or similar methods, are also not always practical or effective, especially in the absence of an atmosphere. Resistance gradients and hysteresis phenomena in the atmosphere disallow reliable discharge. Methods that drain excess static charges require electrical bonding to an earth ground, and are not effective in areas where bonding to ground is impractical, where charge dissipation is imperfect, or where an earth ground doesn't exist.